Particle irradiation apparatus, particle beam irradiation method and particle treatment system

Abstract

A particle irradiation apparatus and a particle beam irradiation method that controls the energy and irradiation dose of a particle beam to form a high dose region having a high uniformity of depth-directional spread (Spread Out Bracici Peak, referred to as SOBP). A SOBP having a steep falling edge of the dose distribution on the deep side from the body surface is formed based on a method of superimposing SOBPs each having a small dose distribution width to form a desired SOBP. An energy-spread-device forms a first SOBP having a small dose distribution width; and an energy spread device 2 forms a second SOBP having a small dose distribution width and a steep falling edge of the dose distribution at the deepest portion from the body surface. The thus formed SOBPs are superimposed to form a SOBP having a length suitable for the target region.

Description

BACKGROUND OF THE INVENTION[0001]1. Field of the Invention[0002]The present invention relates to a particle irradiation apparatus, a particle beam irradiation method and a particle treatment system. More particularly, the present invention is concerned with a particle irradiation apparatus, a particle beam irradiation method and a particle treatment system which are suitable for forming a high dose region in a dose distribution by use of a ridge filter.[0003]2. Description of the Related Art[0004]A particle treatment system, for example, a proton-beam treatment system, is one of the effective means for cancer treatment and is expected to be more increasingly used in the future. With the proton-beam treatment, it is demanded that the dose distribution in an affected part of patient's body (target region) be controlled to a uniform or predetermined state.[0005]Methods of controlling the dose distribution to a uniform state, etc., include using a scatterer to spread out a proton beam o...

AI Technical Summary

Benefits of technology

[0011]An object of the present invention is to provide a particle irradiation apparatus, a particle beam irradiation method and a particle treatment system which make it possible to form a combined SOBP having a steep falling edge of the dose distribution on the deep side from the body surface and perform beam irradiation in a short time based on a method of superimposing SOBPs each having a small dose distribution width to form a desired SOBP.

[0019]This method makes it possible to form a SOBP having a steep falling edge of the dose distribution on the deep side from the body surface based on the method of superimposing SOBPs each having a small dose distribution width to form a desired SOBP.

[0021]This method makes it possible to form a SOBP having a steep falling edge of the dose distribution on the deep side from the body surface based on the method of superimposing SOBPs each having a small dose distribution width to form a desired SOBP.

[0024]In accordance with the present invention, it becomes possible to form a SOBP having a steep falling edge of the dose distribution on the deep side from the body surface based on the method of superimposing SOBPs each having a small dose distribution width to form a desired SOBP.

Problems solved by technology

However, with the method of forming SOBPs each having a small dose distribution width and combining them to form a desired SOBP, if the Bragg peak width is spread out in order to reduce the number of layers and accordingly shorten irradiation time, the dose distribution at a boundary of a SOBP on the deep side of the irradiation region is not sharp, and there arises a problem that the falling edge of the dose distribution on the deep side from the body surface becomes not steep.

If SOBPs each having a small dose distribution width are produced in order to avoid this, there also arises a problem that the number of layers increases, resulting in a prolonged irradiation time.

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